Wall clocks and the like are commercially available which provide for remote resetting or remote synchronization, in order that the time displayed at a particular location will be accurately synchronized with time signal information broadcast from a central control point. A number of systems utilized for this purpose involve the reception and processing of timing information that is constantly broadcast from government operated radio stations, such as WWVB, on a 60 kHz time signal.
There are areas in the United States where the signal strength of the time signal is relatively weak or subject to interference. Furthermore, the ferrite antennas typically used in radio-controlled clocks for receiving the time signal are directional in nature and require proper location placement and alignment. Without such proper placement and alignment, the timing information cannot be recovered from the time signal.
Because the WWVB time signals do not account for time zones, another challenge facing radio-controlled clock designers is to provide a method for setting the initial clock time that accounts for the time zone in which the clock is located. Prior art clocks include various methods of adjusting for different time zones such as including time zone switches for setting the desired time zone. Typically, these prior art clocks require optical and/or mechanical sensing of gear position to provide clock hand position information to a controller, which adjusts the clock hands to the time zone input by the clock user. However, the sensing component costs and extra assembly costs due to difficulties in aligning the clock hands with the position sensors during assembly make these prior art systems costly. In addition, slippage or misalignment of the position sensors during shipping or use can cause the clock to fail or become inaccurate.
Thus, there is a need for a method and apparatus for ensuring that a radio-controlled clock is properly receiving the broadcast time signal. There is also a need for an accurate and reliable method for setting a radio-controlled clock, which accounts for different time zones.